This invention relates to cordless telephones, and more particularly, to providing a telephone with an initial set of communications parameters at the time of manufacture and for providing provisions for changing communications parameters when the cordless telephone is placed in service or is already in service.
Cordless telephones normally include a base station and a handset which communicate over a radio frequency communications channel. Federal regulations provide for such communications to be carried out on any of a set of predefined channels. There are different bands of channels available for cordless telephone use. A band known as the CTO band includes 25 channel pairs, designated channels 1-25. Of these, only channels 16-25 can be used without first monitoring to check whether the channel is occupied. Most 25-channel CTO cordless telephones therefore start their communications on one of the channel pairs. In addition, cordless telephone manufacturers have implemented a security code feature in which a security code is included in transmissions between the base station and the handset to distinguish one call from another on the same communications channel. The communications channel and security code will hereinafter be referred to as communication parameters.
In addition to the aforementioned communication parameters, some applications of cordless telephones are preferably provided with brand line prompt information so that a user can observe on a display on the telephone, a prompt, indicative of the service provider and the like.
Normally, cordless telephones are manufactured with preprogrammed communications default parameters including initial channel selections. However, in order for a base and a handset to communicate with each other, they both must be programmed to communicate on the same channel. This requires that the base be matched to the handset at the time of shipping to ensure both are programmed appropriately. This increases the cost of production and forces the user to purchase a new base and a new handset in the event that one or the other must be replaced.
Another problem which occurs in cordless telephones is interference due to neighbouring telephones or other radio frequency equipment. When such interference occurs on a given channel, it is desirable to change the programming in the base and handset to cause the base and handset to communicate on a different channel.
It would be desirable if a base/handset pair could automatically locate a channel with a minimum amount of background noise and automatically program the base and handset to communicate on such channel.